JPH02304284A - Electromagnetic valve drive control device - Google Patents

Abstract

PURPOSE:To improve the hydraulic responsibility by superposing the dither current having the dither characteristic set in response to the current level to the driving current on the basis of the driving current command to apply it to an electromagnetic valve. CONSTITUTION:I an area where the current level of the driving current command from a driving current command output means (c) is small, the effect of dither is set by a dither characteristic setting means (d) so as to be the predetermined value, and the dither current is superposed to the driving current by a valve drive control means (e) to apply the driving current with dither to an electromagnetic valve (b). Consequently, the electromagnetic force and the hydraulic reaction force are acted on a valve spool, and in an area where the current level is small, hysteresis of the electromagnetic valve (b) for pressure-governing the input oil pressure to the control oil pressure to be fed to an hydraulic actuator (a) is erased by the dither current to improve the hydraulic responsibility. On the other hand in an area where the current level is large, the effect of dither is set in the weak characteristic to reduce the generation of oscillation and noise.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention provides an electromagnetic valve for use in an actuator system, such as an auxiliary steering control system or an active suspension control system that auxiliarily steers at least one of the front wheels and rear wheels during front wheel steering. The present invention relates to an electromagnetic valve drive control device that is applied to various control systems in which a valve is used.

(Prior Art) As a rear wheel steering control system to which an electromagnetic valve drive control device is applied, for example, the applicant of the present application has previously proposed
There is a system proposed by No. 165932.

This rear wheel steering control system determines a target rear wheel steering angle that provides optimal vehicle dynamic characteristics based on the front wheel steering angle and vehicle speed during corner steering, and uses a hydraulic actuator system to adjust the rear wheels to the front wheels in phase or in phase with each other. Steering control is used to improve steering stability compared to, for example, front-wheel steering vehicles (2WS vehicles).
It is designed to improve steering response.

(Problem to be Solved by the Invention) Such a rear wheel steering control system applies a drive current based on a drive current command signal from a rear wheel steering control unit to an electromagnetic valve from a solenoid drive circuit, and inputs it in this electromagnetic valve. Since the hydraulic pressure is regulated to the control hydraulic pressure and this control hydraulic pressure is supplied to the hydraulic actuator to control the steering of the rear wheels, when looking at the control hydraulic pressure vs. drive current characteristics, the hydraulic pressure increases as shown in Figure 8. There is hysteresis in the drive current when the oil pressure is lowered and when the oil pressure is lowered, and this hysteresis deteriorates the oil pressure response, making it impossible to obtain initial steering stability and steering response.

Therefore, the drive current is changed to a dithered drive current, and the dither
There is a plan to increase the effectiveness of the dither by increasing the amplitude to substantially reduce the hysteresis and improve the hydraulic response.

However, if the dither effect is strengthened over the entire range of the drive current, the hydraulic response will improve, but the dither current, which is more effective in the large current range, will cause oil pressure fluctuations to become rougher, causing vibrations and abnormal noises. Occur.

The present invention has been made with attention to the above-mentioned problems, and is directed to an electromagnetic valve drive control device having an electromagnetic valve actuated by a drive current in an actuator system. The objective is to achieve both reduction of vibration and abnormal noise generation.

(Means for Solving the Problems) In order to solve the above problems, in the electromagnetic valve drive control device of the present invention, the drive current applied to the electromagnetic valve is a dithered drive current, and the dither characteristics are set such that the current level is large. This was used as a means of setting the characteristics to be less effective in the area.

That is, as shown in the complaint diagram in FIG. 1, there is a solenoid valve b that applies electromagnetic force and hydraulic reaction force to the valve spool to adjust the input hydraulic pressure to the control hydraulic pressure that is sent to the hydraulic actuator a, and a predetermined control hydraulic pressure. drive current command output means C for outputting a drive current command to be obtained; dither characteristic setting means d for setting a dither characteristic determined by frequency and amplitude to a characteristic in which the dither effect is weak in a region where the current level is large; Valve drive control means e applies a dithered drive current to the electromagnetic valve b, in which a dither current having a set dither characteristic is superimposed on a drive current based on a drive current command. shall be.

(Function) In a region where the current level of the drive current command output from the drive current command output means C is small, the dither characteristic setting means d sets the dither effectiveness to a predetermined value,
From the valve drive control means e, a dithered drive current is applied to the electromagnetic valve b, in which a dither current having a set dither characteristic is superimposed on a drive current based on the drive current command.

Therefore, in electromagnetic valve b, which applies electromagnetic force and hydraulic reaction force to the valve spool to adjust the input hydraulic pressure to the control hydraulic pressure sent to hydraulic actuator a, there is hysteresis in the control hydraulic pressure-drive current characteristic, but this hysteresis is optimal for effectiveness. The current level of the drive current command is substantially reduced by a dither, and hydraulic responsiveness is improved in a region where the current level of the drive current command is small.

Further, in a region where the current level of the drive current command output from the drive current command output means C is large, the dither characteristic setting means d sets the dither to a weak characteristic, and the valve drive control means e outputs a A dithered drive current in which a dither current having a set dither characteristic is superimposed on a drive current based on the current command is applied to the electromagnetic valve b.

Therefore, when the dither effect is increased over the entire drive current range, oil pressure fluctuations that occur in the large drive current range are suppressed, and vibrations and abnormal noises are reduced in the large current level range.

By performing the dither change control corresponding to the drive current as described above, it is possible to achieve both improvement in hydraulic responsiveness when the drive current is small and reduction in vibration and noise generation when the drive current is large.

(Example) Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 2 is a diagram showing the overall configuration of a four-wheel steering vehicle equipped with a rear wheel steering control system to which the electromagnetic valve drive control device of the embodiment is applied.

First, the configuration will be explained.

In Figure 2, IL and IR are the left and right front wheels, 2L, and 2R, respectively.
are the left and right rear wheels, and 3 is the steering wheel. The front wheels IL and IR can each be steered by a handle 3 via a steering gear 4, and the rear wheels 2L and 2R can be steered by a rear wheel steering actuator 5, respectively.

The rear wheel steering actuator 5 is a spring center type hydraulic actuator, and when supplying hydraulic pressure to the chamber 5R,
The rear wheels 2L and 2R are respectively steered to the right by a steering angle proportional to the pressure, and when hydraulic pressure is supplied to the chamber 5L, the rear wheels 2L and 2R are respectively steered to the left by a steering angle proportional to the pressure. do.

An electromagnetic proportional rear wheel steering control valve 6 for controlling the hydraulic pressure to the actuator chambers 5L and 5R is provided, and this valve 6
applies electromagnetic force and hydraulic reaction force to the valve spool,
It is a self-servo type that adjusts the input oil pressure to the control oil pressure that is sent to the actuator 5, and in case of functional problems, it has a configuration in which variable throttles 6a, 6b, 6c, and 6d are bridge-connected, and a pump is connected to this bridge circuit. 7. Connect the oil passages 9 and 10 from the reservoir 8 and the actuator chambers 5L and 5R, respectively.

This control valve 6 is further provided with a solenoid 6L.

6R, when these solenoids 6L and 6R are OFF, the variable throttles 6a, 6b and 6c, 6d are fully opened to make both actuator chambers 5L, 5R unpressurized.
When turned on by dithered drive current IL* or IR* of solenoid 6 [or 6R], variable aperture 6c, 6d or 6a
, 6b to the opening degree according to the current value, and a dithered drive current IL* or ■ is applied to the actuator chamber 5L or 5R. *
The hydraulic pressure shall be supplied according to the current value. As mentioned above, this oil pressure is applied to the rear wheel 2L by an angle corresponding to the value.
Turn 2R in the corresponding direction.

Oil passages 9 and 10 between the electromagnetic proportional rear wheel steering control valve 6 and the rear wheel steering actuator 5 (the oil passages before and after the cut valve 20 are 9-1.9-2 and 10-1.10-, respectively).
In the middle of the solenoid opening/closing valve structure, there is a
The valve 20 is inserted.

This cut valve 20 is a normally closed type, and the ignition O
When the solenoid drive current IF is not supplied to the solenoid 20a due to FF or failure, the oil passage 9-1.9
-2 and 10-1 and 10-2 are shut off, when the rear wheel steering control is being performed normally, and when the solenoid drive electric current is being supplied, the oil path 9-1° 9-2 and 10-1, 10-2 are communicated.

Incidentally, when the cut valve 20 closes, the failure occurs when the microcomputer goes out of control, when a sensor malfunctions, or when the solenoids 6L and 6R of the control valve 6 are disconnected or short-circuited.When the cut valve 20 fails, an alarm is issued along with the close operation of the force/cut valve 20. The lamp 21 is turned on.

Applying a dither drive current * or ■8* to the control valve solenoids 6L and 6R, applying a solenoid drive current ■ to the cut valve solenoid 20a, and applying an ON/OFF signal to the alarm lamp 21. The rear wheel steering control unit 30 includes, as sensors for providing input information, a steering wheel steering angle sensor 40 that detects the steering direction and steering angle of the steering wheel using a steering angle signal θ;
The neutral position signal θ is the neutral position of the steering wheel within a predetermined steering angle range. A steering wheel neutral position sensor 41 that detects vehicle speed using a vehicle speed signal V, a vehicle speed sensor 42 that detects vehicle speed using a vehicle speed signal V, an ignition switch 43, and the like are connected.

In this rear wheel steering control unit 30,
As shown in the block diagram of FIG.
a, digital microcomputer 31, D/A converter 30b, solenoid drive circuit 30c, solenoid drive circuit 30d, display drive circuit 30e, m minute path 30
f. Even if the watch dog timer 309 is provided, it will work.

The digital microcomputer 31 includes, as internal circuits, a front wheel steering angle calculation circuit 31a, a rear wheel steering angle calculation circuit 31b, a θR-I conversion circuit 31C, a dither current signal setting circuit 31d, a signal addition circuit 31e, and a load model 3.
1f, a comparison circuit 319, and a failsafe circuit 31h.

Next, the effect will be explained.

(A) Fail Detection Operation FIG. 4 is a flowchart showing the flow of fail detection operation of the solenoid drive control system of the control valve solenoid 61.6H, which is started after the ignition switch 43 is turned on.

*Fail detection cancellation processing steps 50 to 52 are fail detection cancellation processing steps.

In step 50, a load model 31f is created that simulates the same response as the control valve solenoids 6L and 6R, which are the actual loads.
In, the drive current signal IL, 1. is input.

In step 51, in the load model 3+f using the digital filter, input signals IL, 1. are converted into output signals r-' and IR' by filtering processing.

In step 52, the comparator circuit 319 determines whether the input/output signal difference Δ■ of the load model 31f is less than a threshold value, and determines that ΔI> is present and that the input is in an input transient state where the input changes rapidly. If so, jump to step 56,
The fail detection process from step 53 onward is canceled, and when it is determined that Δwork≦ and the input change is small, the process proceeds to the fail detection process from step 53 onwards.

That is, the control valve solenoids 6L and 6R are inductance loads, and the control valve solenoids 6L and 6R are inductance loads.
, 6R solenoid drive circuit 30c is a constant current circuit that uses a fixed power supply voltage E, so the solenoid drive circuit 3
In response to a sudden input to 0c, the current is regulated by the transient response of the inductance, and the constant current circuit is saturated and outputs the power supply voltage E.

As a result, when the input to the solenoid drive circuit 30c is transient, the solenoid drive circuit 30c outputs a drive current with no dither, and the pulse signal disappears during the input transient, resulting in erroneous fail detection.

Therefore, when the input to the solenoid drive circuit 30c is transient, a load model 31f that simulates the same response as the control valve solenoids 6L and 6R is used to determine whether or not the input is transient at a stage before the solenoid drive circuit 30c. The solenoid drive circuit 3
Erroneous fail detection by monitoring the presence or absence of dither during input transition to 0c is prevented, and highly accurate fail detection is ensured.

*Fail detection processing steps 53 to 57 are fail detection processing steps.

In step 53, in the differentiating circuit 30f, the dithered drive currents IL'' and IR* applied to the control valve solenoids 6L and 6R are branched from the harness connecting the solenoid drive circuit 30c and the control valve solenoids 6L and 6R. A pulse-like signal corresponding to the dither is obtained by inputting the signal and performing differential processing.

In step 54, the watchdog timer 30
At step 9, the number of fixed-time pulses is counted based on the dither-compatible pulse signal input from the differentiating circuit 30f.

In step 55, the fail-safe circuit 31h determines whether the pulse count from the watch dog timer 309 is a normal pulse count according to the dither frequency, and if it is a normal pulse count, The process proceeds to step 56, where a normal command to maintain the wheel engagement steering control is output, and if the count is zero, the process proceeds to step 57, where a fail command to start a fail operation, which will be described later, is output.

That is, if the harness connecting the solenoid drive circuit 30c and the control valve solenoids 6L and SR is disconnected, the drive current will no longer flow through the harness, and if the harness is short-circuited, the harness will not respond to the fixed power supply voltage E. A linear constant current flows.

In other words, in any fail mode, the dither disappears, so the control valve solenoid 6L
, 6R are inputted with dithered drive currents IL*, I□* from the harnesses, and by monitoring the presence or absence of dithering, it is possible to detect failures such as disconnections and short circuits in the harness.

The dithered drive currents IL* and IR* used for this fail detection are currents obtained by superimposing dithered currents, regardless of the current value of the drive current, so the dithered drive current 1 ．． Even when the current values of *, ■, and * are zero, the differential signals of the drive currents IL*, Ig, and Ig become pulse signals, making it possible to detect failures.When detecting failures by comparing conventional linear drive currents, As shown in the figure, if the harness is disconnected when the drive current is zero or if the harness is short-circuited while the drive current is flowing, fail detection will not become impossible, and fail detection is not subject to timing restrictions. becomes possible.

Therefore, while it is advantageous in terms of cost when using a large number of comparison circuits, it is possible to always detect disconnections and short circuits in the harness with high detection accuracy regardless of whether the drive current is flowing or not. .

Further, a digital microcomputer 31 having a dither current signal setting circuit 31d in its internal circuit and control valve solenoids 6L, 6R based on dither drive current signals (IL'') and (IR*) from the digital microcomputer 31 are provided. and a solenoid drive circuit 30c that produces a dithered drive current IL111.I, * applied to the dithered drive current IL111. Since we are trying to do this, the differential circuit 30
A single dither monitoring circuit using f, watchdog timer 309, etc. can detect failures of both the digital microcomputer 31 and the solenoid drive circuit 30c.

That is, when the digital microcomputer 31 fails to operate normally, the microcomputer 3
The dither current signal (2) is generated by the dither current signal setting circuit 31d which performs the setting operation according to the normal operation of the dither current signal (1). If this setting is not made, dither monitoring detects whether the digital microcomputer 31 is normal or abnormal.

In addition, when the solenoid drive circuit 30c fails, the dithered drive current IL", IR" or dither disappears, and the solenoid drive circuit 3
0c normal/abnormal is detected.

As described above, the fail detection device of the embodiment is capable of detecting not only failures such as wire breakage and short circuits in the harness but also failures of the solenoid drive control system including the digital microcomputer 31 and the solenoid drive circuit 30c using a single dither. - Can be detected by monitoring means.

(b) Rear wheel steering control and fail-safe operation Figure 5 is 5.
2 is a flowchart showing the flow of rear wheel steering control operation and failsafe operation performed by the control cycle of m5ec.

In step 60, it is determined whether this is the first time the control is activated.

In the step 61, necessary initialization processing is performed, such as setting the dither flag D to D=0 and setting the timer values TP, T, to T=0.

In step 62, it is determined whether or not a fail command is output. If the fail command is not output, the wheel turning control operation from step 63 onwards is performed, and when the fail command is output, the steps from step 82 onwards are performed. Fail-safe operation is performed.

*In the rear wheel steering control activation step 63, the steering angle signal θ and the neutral steering angle signal θ. and vehicle speed signal V are read.

In step 64, the steering angle signal θ and the neutral steering angle signal θ are determined. Neutral steering angle estimate θ obtained based on .

and the steering angle signal θ, the front wheel steering angle signal θ is obtained.

is calculated using the following formula.

θ,=10−θcvl In step 65, a target rear wheel steering angle signal θ1 is calculated based on the vehicle speed signal V and the front wheel steering angle signal θF. In step 66, the target rear wheel turning angle signal θ is converted into a drive current signal IL or IR using a θ, -I characteristic table given in advance.

In step 67, the dither flag D is set to D=0 or D=1.
is determined, and when D=O, -I every 50m5ec
Step -68 to apply a dither current signal of 0 to step 73, and when D=1, 50m5e
Earthworks every c. Step 7 of applying a dither current signal of
4 - Proceed to step 79.

In step 68, the dither current signal setting circuit 31d sets the drive current signal based on the drive current signal IL or signal 8 inputted from the θM-1 conversion circuit 31c and the dither current signal characteristics shown in FIG. , or a dither current signal corresponding to ■8. (For example, dither current 50
(e.g., a signal corresponding to mA) is set.

In step 69, the timer value T is incremented by 1 each time the control is activated.

In step 70, it is determined whether or not the timer value T is above 1114. If the timer value T is 11, the process proceeds to step 73, where the signal addition circuit 31e adds the dithered drive current signal (IL'l) according to the following equation. '), <r-)
is calculated, and when ■work=11, in step 71 D=
It is rewritten to 0, and in step 72 it is rewritten to Tp''O.

(Ill) = IL-IQ (IR”) = IRI.

In step 74, similarly to step 68, in the dither current signal setting circuit 31d, the θq-1 conversion circuit 31
A dither current signal 1° corresponding to the drive current signal or IR is set based on the drive current signal I or IF1 inputted from the drive current signal I or IFl input from the drive current signal I or IF1 and the dither current signal characteristics shown in FIG.

In step 75, the timer value {circle around (2)} is incremented by one each time the control is activated.

In step 76, it is determined whether the timer value ■2 is greater than or equal to 11. If Tp<II, the process proceeds to step 79, where the signal addition circuit 31e calculates the dithered drive current signal (Ill), ( Ill) is calculated, and when T,=11, it is rewritten to D=0 in step 77, and rewritten to T,=O in step 78.

(Ill) = IL + 1° (Ill) = IR + 10 In step 80, based on the signal obtained in step 73 or step 79, the solenoid drive circuit 30
At c, a dithered drive current, * or Ill, in which a dither current is superimposed on the drive current, is output to the control valve solenoid 6L or 6th.

In step 81, the cut valve 20 is opened to the valvelenoid 20a (the solenoid drive current I due to the ON signal is output).

Therefore, in the rear wheel steering control operation, for example, as shown in FIG. When phase reversal control is performed, the rise of the yaw rate is improved by actively applying cornering force in the direction of yaw generation, and after sufficient yawing is obtained, the rear rotation is shifted to the same phase side. By controlling the increase in yaw rate by turning the steering wheel, the vehicle sideslip angle is suppressed, increasing steering stability and providing high steering response.

In addition, in this first-order advance phase inversion control, the phase inversion timing becomes earlier as the vehicle speed increases, and at high speeds, the control is almost the same as in-phase control, so it is especially low.

Effective in medium speed range.

In addition, when setting the dither, it is set to a constant frequency that changes every 50 m5ec, but the dither amplitude, which is determined by the magnitude of the dither current, is determined by the drive current signal IL or the dither amplitude, as shown in Figure 6. In the region where the current level of 1 is small below I0, the dither effect is set to a large amplitude,
When the drive current signal I or the current level of the circuit 8 exceeds Io, the amplitude is gradually reduced and the dither effect is weakened, so that the following effect is exhibited.

The control valve 6 is a self-servo type that applies electromagnetic force and hydraulic reaction force to the valve spool to adjust the input hydraulic pressure to the control hydraulic pressure sent to the actuator 5, so as shown in FIG. Although there is hysteresis in the characteristics, in the region where the current level of the drive current signal IL or Ill is small below I0, this hysteresis is effectively reduced by the dither with a strong effect on the amplitude ±0.1, as shown in Figure 9. The hydraulic response is improved.

Also, the current level of the drive current signal wire or wire 8 is ■.

In the range exceeding 100 kHz, for example, as shown in FIG. 10, a less effective dither with an amplitude of ±0.05 A is used to reduce imaging and abnormal noise generation.

As described above, the drive current signal switch or the drive current signal switch 8 improves the hydraulic response when the drive current signal is small and the drive current signal I
L or I8 can simultaneously reduce vibration and abnormal noise when a large drive current signal is used.

Furthermore, the current level of the drive current signal IL or IR is 1
, the amplitude is gradually reduced when it exceeds ,
While ensuring the maximum hydraulic responsiveness, vibrations and noises exceeding a predetermined level are suppressed from occurring by reducing the vibrations and noises according to the degree of occurrence.

The dither current is used for the above-mentioned fail detection purpose, for the purpose of simultaneously improving the hydraulic response and reducing vibration and abnormal noise, and for suppressing stick-slip by constantly giving a subtle vibration to the spool of the control valve 6. Although the dither current is superimposed on the drive current for multiple purposes, the dither current with the amplitude and frequency set in the example (amplitude of ±0.1 A or less, frequency of 100 Hz) satisfies all of these purposes. Therefore, the original rear wheel steering control by the control valve 6 is not affected.

*In the fail-safe operation step 82, a solenoid drive current I based on an OFF signal that closes the cut valve 20 is output to the valve solenoid 20a.

In step 83, a lighting signal (ON) is applied to the alarm lamp 21.
is output.

In step 84, it is checked whether the elapsed time from the fail-safe command has reached a predetermined time ΔTo (for example, 150 m5ec), and ΔTo≧△■. When this happens, a command is output in step 86 to turn off the dithered drive current IL* or 8* of the solenoid 6L or 6R of the control valve 6.

Therefore, in fail-safe operation, the oil pressure is cut by the cut valve 20, and then the oil leakage from the cut valve 20 is used to gradually return the rear wheels to the neutral position, so in the event of a fail Sudden changes in vehicle behavior are prevented.

Although the embodiment has been described above based on the drawings, the specific configuration and control contents are not limited to this embodiment.

For example, in the embodiment, an example of a rear wheel steering control system was shown as an application system of the electromagnetic valve drive control device, but an auxiliary steering control system and an active suspension control system that control steering of the front wheels and rear wheels using actuators during front wheel steering are also shown. Needless to say, the present invention can be applied to any control system having an electromagnetic valve operated by a drive current in an actuator system, such as a torque split control system or an anti-lock brake control system.

In addition, in the embodiment, an example was shown in which the dither characteristic for the drive current is changed by the dither amplitude, but just as increasing the dither amplitude increases the dither effect, the dither frequency also increases. Utilizing the characteristic that the dither effect is strong on the low frequency side and weak on the high frequency side, it is also possible to control the frequency by changing the frequency while keeping the amplitude constant, or to control the dither that is optimal in terms of both amplitude and frequency. −
This may also be an example of setting the effect characteristics.

Furthermore, due to the inductance characteristics of the control solenoid, the dither amplitude increases as the drive current increases. Contents for controlling correction of dither characteristics may be added.

In addition, when the oil temperature is high, the electromagnetic valve causes problems such as vibration and abnormal noise due to its low viscosity characteristics, and when the oil temperature is low, the problem of poor response due to its high viscosity characteristics occurs.
The oil temperature may be monitored by an oil temperature sensor or the like, and correction control may be added to strengthen the dither effect when the oil temperature is low and weaken the dither effect when the oil temperature is high.

(Effects of the Invention) As explained above, in the electromagnetic valve drive control device of the present invention, the drive current applied to the electromagnetic valve is a dithered drive current, and the dither characteristics are set as follows: As a result, in a solenoid valve drive control device that has a solenoid valve operated by a drive current in the actuator system, it improves hydraulic response at low drive currents and reduces vibration at large drive currents. The effect is that it is possible to achieve both the reduction of noise and the generation of abnormal noise.

[Brief explanation of drawings]

Fig. 1 is a diagram illustrating the complaints of the electromagnetic valve drive control device of the present invention, and Fig. 2 is a diagram showing the overall configuration of a four-wheel steering vehicle equipped with a rear wheel steering control system to which the electromagnetic valve drive control device of the embodiment is applied. , Figure 3 is a block circuit diagram of the rear wheel steering control unit of the rear wheel steering control system, Figure 4 is a flowchart showing the flow of the fail detection processing operation in the implementation device, and Figure 5 is the rear wheel steering control operation. and a flowchart showing the flow of fail-safe operation, Fig. 6 is a dither current signal characteristic diagram for the drive current signal, Fig. 7 is a time chart showing an example of rear wheel steering control, and Fig. 8 is control oil pressure - drive current characteristic. 9 is a time chart showing an example of a dithered drive current when a small drive current signal is output, and FIG. 10 is a time chart showing an example of a dithered drive current signal when a large drive current signal is output. . a...Hydraulic actuator b...Solenoid valve C...Drive current command output means d...Dither characteristic setting means e...Valve drive control means

Claims (1)

[Claims] 1) An electromagnetic valve that applies electromagnetic force and hydraulic reaction force to a valve spool to adjust the input hydraulic pressure to a control hydraulic pressure that is sent to a hydraulic actuator, and a drive that outputs a drive current command to obtain a predetermined control hydraulic pressure. current command output means; dither characteristic setting means for setting a dither characteristic determined by frequency and amplitude to a characteristic in which the dither effect is weak in a region where the current level is large; An electromagnetic valve drive control device comprising: valve drive control means for applying a dithered drive current in which dither currents having characteristics are superimposed to the electromagnetic valve;